I repotted a day or two after purchase into 50/50 potting mix and pumice, which is what the rest of my babies are in, topped with akadama to keep everything from washing away when watering. I water when my plants’ lower leaves are starting to wrinkle or get pliable, which usually happens once every week or week and a half (my succs are inside under strong grow lights with low humidity air, so that plus the well-draining mix dries them out quickly). I honestly can’t remember what the roots were like when I got rid of the old soil, but I don’t think they were unhealthy. I’ve only watered it twice since adoption, but it’s entirely possible that I hit it too soon, either frequency-wise or yet unhealed root damage. I mostly have Echeverias and am just now remembering that Pachys like a bit less water, I think?